Modern commercial aircraft typically have a number of doors that require opening for emergency evacuation and in non-emergency situations, such as normal passenger entry and exit and routine servicing and maintenance. It is desirable to maximize the speed and ease of the opening of the door for emergency evacuation. In some aircraft, the doors are always opened manually. Counter-balance springs may be provided to assist the manual opening. Another approach that has been used is to provide powered door opening. This generally achieves greater ease and speed of opening in an emergency situation, but known powered door systems have a number of drawbacks. These drawbacks include relative complexity and number of parts, high maintenance requirements, weight, and lack of flexibility. In addition, known systems may not provide outward and sideward door movement in which the door remains parallel to the fuselage so that, in a fully open position, it allows maximum use of the door opening for emergency egress. In known powered doors, high pressure gas is usually the energy source and is applied by means of an actuator that is either rotary or linear. The linkage between the door and door frame may be a direct bolted linkage, a rigid adjustable rod, a chain and sprocket, or a helical cam. In known systems, each of these types of linkage is a system separate from the other door mechanisms.